1. Field of the Invention
The present invention relates to a vehicle air-conditioning control apparatus.
2. Background Art
A vehicle air-conditioning control apparatus is provided with: a cool-air generator comprising a compressor, a condenser and an evaporator; and a warm-air generator utilizing an engine coolant as a heat source, and is configured to control an air mix damper to change a mixing ratio between cool air and warm air to thereby obtain conditioned air having a desired temperature. Then, the conditioned air will be supplied into a vehicle interior (vehicle passenger compartment) by a blower, wherein a supply amount of the conditioned air is changed by changing a rotational speed of the blower. Generally, the compressor is driven by an engine, and a water pump for circulating the coolant is also driven by the engine. Thus, when the engine is stopped, the compressor and the water pump are stopped, so that a cool-air generating function and a warm-air generating function are ceased.
Further, in the field of vehicle air-conditioning control apparatuses, an automatic air-conditioning type configured to automatically control an actual vehicle interior temperature to conform to a target vehicle interior temperature has become mainstream. The air-conditioning automatic control is performed in accordance with parameters indicative of an environmental condition inside a vehicle interior, an environmental condition outside the vehicle interior, and a passenger's manual air-conditioning operation state (particularly, a manual set value of the target vehicle interior temperature), to automatically set a blow temperature of conditioned air, a blow port of conditioned air, a blow amount of conditioned air and others.
Meanwhile, in recent vehicles, with a view to improving fuel economy, a technique of automatically stopping an engine when a vehicle is stopped or at a very low vehicle speed just before stopping the vehicle, so-called “idling stop”, has been increasingly employed. The idling stop is executed only if a preset initiation condition is satisfied. Generally, the initiation condition is set as a condition that all of a plurality of sub-conditions, such as: a sub-condition that a vehicle speed is zero (the vehicle is in a stopped state); a sub-condition that a brake is in an operated state; a sub-condition that an accelerator is in a non-operated state; and a sub-condition that a transmission is in a D position, are satisfied.
While the cool-air generator and the warm-air generator are stopped when the engine is automatically stopped, it is desirable to continue the air-conditioning control as much as possible, even during automatic stop of the engine. For this purpose, for example, JP 2010-143552A discloses, even during automatic stop of an engine, determining a target opening degree of an air mix damper, and drivingly controlling the air mix damper to allow an opening degree thereof to conform to the target opening degree.
In this context, it was found that, if the air-conditioning automatic control is continued during automatic stop of the engine, a noise (undesired sound) problem occurs. This will be described below. Upon stop of the engine, the cool-air generator in a cold state will gradually become warmer, and the warm-air generator in a warm state will gradually become colder. Thus, even in the same surrounding environment, during automatic stop of the engine, the target opening degree is frequently changed as compared to during running of the engine, so that an air mix damper-driving actuator will be alternately placed in driven and un-driven states frequently. Then, a passenger will feel noise generation every time the actuator is driven. In particular, as compared to during running of the engine, a surrounding noise level becomes lower during automatic stop of the engine, so that the passenger becomes more sensitive to drive noise of the actuator.